package demo4;

public class Computer {

    public void powerOn() {
        System.out.println("打开电脑...");
    }

    public void powerOff() {
        System.out.println("关闭电脑...");
    }


    public void useDevice(USB usb) {
        usb.openDevice();
        if(usb instanceof KeyBoard) {
            KeyBoard keyBoard = (KeyBoard)usb;
            keyBoard.input();
        } else if (usb instanceof Mouse) {
            Mouse mouse = (Mouse)usb;
            mouse.click();
        }
        usb.closeDevice();
    }

}
